Amazon.com, the Seattle-base online retailer, gave a first glimpse this morning of its still under-construction warehouse in Livonia: Millions of items — under one roof — ready to ship to homes throughout the Midwest and, if need be, nationally.

"It's colossal," said Dennis Wright, Livonia's Mayor, who was among the 30 or so dignitaries and journalists on the tour of the 1-million square-foot building off Amrhein Road. "We're looking at the 21st century of retail and how much it is going to change."

The Livonia facility, what Amazon calls a fulfillment center, is one of a handful Amazon is building in southeast Michigan to expand its delivery network in the state and speed the time it takes to deliver packages to customers, especially those with its Prime service.

It is expected to open in October and create up to 1,500 jobs that pay an average of about $14 an hour, and include benefits.

Amazon said it has more than 75 large distribution centers in North America.

The new in Livonia center, which was mostly still empty as workers poured cement and assembled fixtures, will be filled with 5.4 million cubic feet of racks and long stretches of conveyor belts, as dozens of trucks unload and load packages daily.

The center will ship large packages, mostly throughout the Midwest, but could send them to other places in the United States.

In addition to the center in Livonia, Amazon is expected to open a smaller distribution center in Hazel Park employing about 100 people by the fall; a large center in Romulus employing about 1,600 people within a year, and a large center in Shelby Township, which would employ 1,000 people and could receive financial incentives from the state.

Amazon opened a small center in Brownstown Township in 2015, which employs about 300 people and is being remodeled.